XPS Study of "infinite Chain" Ca$\text{}_{2}$CuO$\text{}_{3}$ and Ca$\text{}_{0.5}$Sr$\text{}_{0.5}$CuO$\text{}_{2}$ Compounds

Al K$\text{}_{α}$ excited photoelectron spectra (X-ray photoelectron spectroscopy) of the O 1s, Cu 2p, Ca 2p, Sr 3d core levels were measured for "infinite chain" Ca$\text{}_{2}$CuO$\text{}_{3}$ and Ca$\text{}_{0.5}$Sr$\text{}_{0.5}$CuO$\text{}_{2}$ compounds. The analysis indicates that for Ca$\text{}_{2}$CuO$\text{}_{3}$ the surface electronic structure is strongly influenced by a humid atmosphere. The surface layer is formed predominantly by copper hydroxide. The minor features of Cu 2p and O 1s are characteristic of the bulk bonding states. The valences of the Cu, Ca, and Sr atoms are close to 2+. The core electron binding energies (≈ 934 eV peak) are due to the 2p$\text{}_{3}\text{}_{/}\text{}_{2}$ 3d$\text{}^{10}$L$\text{}^{1}$ configuration of Cu(II) ions in the square planar coordination for both samples.